On SPARC, we still have checks for 64-bit capable hardware (doing clunky string-comparisons on dates to see if the boot prom has been flashed to an appropriate level).
This made sense at the time of the Solaris 7 launch, but people have had over 20 years to update their boot proms. Anyone with such a system (sunfire is being removed as part of IPD5 anyway) should have already updated their firmware.
This only affects a few platforms (E250, E450, E3000-E6000) which straddled the transition.
We also still check for UltraSPARC-I processors, which haven't been supported for 15 years.
Also a webrev which shows the deleted files:
http://cr.illumos.org/~webrev/ptribble/11630/